Alternative method to model an agricultural vehicle's tire parameters

This paper introduces an alternative method to model the tire dynamic parameters of an agricultural vehicle from experimental data sets without the use of conventional test equipment. A Global Positioning System implementing a Real Time Kinematic scheme (RTK-GPS) and an Inertial Measurement Unit (IMU) are used to estimate the vehicle's body sideslip angle and to establish the relation between the tire's lateral forces and slip angles for different soil conditions; in terms of soil moisture content and cone index. To validate the method introduced in this paper, the results obtained from the experimental data sets were compared with an empirical modeling method; which uses a particular form of the relationship between lateral force, normal force and slip angle expressed as an exponential function. Results show that the method introduced in this paper can give a more accurate description of the relation between the tire's lateral forces and slip angles. This knowledge can be applied to improve automatic steering controller systems.